Valve device



A. E. 1-. SCANES. VALVE DEVI CE. 7 APPLICATION FILED NOV. 25. 1918.

1,347,411. I Patented July 20, 1920.

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UNITED STATES PATENT OFFICE.

THE BRITISH WESTINGHOUSE ELECTRIC AND MANUFACTURING COMPANY LIM- ITED, A COMPANY OF GREAT BRITAIN.

Specification of Letters Patent.

VALVE DEVICE.

Patented July 20, 1920.

Application filed November 25, 1918. Serial No. 264,030.

T 0 all whom it may concern:

Be it known that I, ARTHUR EDWIN LEIGH SoANns, a subject oi the King of Great Britain, and a resident of Ashton-on- Mersey, in the county of Chester, England, have invented a new and useful Improvement in Valve Devices, ofwhich the following is a specification.

This invention relates to valve devices particularly applicable for use in connection with apparatus for exhausting air and non condensable gases, and has for its object to provide improved apparatus of this character.

When exhausting apparatus such as a pump or ejector is used to evacuate a receiver it is frequently desirable to have a re lux or non-return valve situated between the exhausting apparatus and the receiver; This valve has for its object to prevent the return of air or gases tothe receiver in the event of the exhausting apparatus failing in its action. In valves of this description the weight of the. valve is usually balanced so as to minimize the pressure difference necessary to actuate the valve. Even in the most carefully made valves, however,

' friction cannot be entirely eliminated and when the pressure difference between the receiver and the evacuating apparatus is small, it may happen that there is a relatively large pressure drop through the valve due to incomplete opening, entailing a loss of efliciency.

In the present invention the improved valve device is provided with means for overcoming the eflect of friction or of the spring or balance weight provided for normally holding the valve on its seat and resulting in incomplete opening of the valve especially when the difference of pressure on either side of the valve is small.

According to the invention a non-return valve in the suction pipe of an exhausting apparatus is connected with a piston work ing in a cylinder, one end of which is in communication with the space on the suction side of the valve and the other end of which is open to the atmosphere or communicates with a source of pressure above atmospheric, the piston being so connected to the valve as to assist in the opening thereof when the pressure on the suction side is recooperating valve 3 of the mushroom type which is held upon said seat by means of a balance weight t acting through a lever 5 which is pivoted to the stem 6 of the valve. The seat 2 may be provided with win s 7 supporting a guide 8 for the valve stem. he

valve stem is enlarged at one part to form a piston 9 whichv cooperates with a cylinder 10 which is, conveniently formed by, an inwardextension of the suction pipe. Additional support may be given to the cylinder by means of the web 11.

The valve stem 6 is formed hollow and communicates on the one hand by means of a port 12 with the space in the cylinder 10 below the piston 9, and on the other hand at the bottom of the stem with the space 13 on the suction side of the valve, that is on the side nearest the pump or ejector. The other end of the cylinder 10, that is to say the space on the upper side of the piston 9, is open to the atmosphere and is provided with a liquid seal 14.

The operation of the device is as follows Before the exhausting device is started and assuming that there is atmospheric pressure throughout the system, the balance weight 4 will keep the valve 3 on its seat 2. On starting the exhausting device a drop in pressure will be produced on the suction side 13 of the valve 3 {and in the lower end of the cylinder 10 which is in communication with this space 13 through the hollow valve stem 6. The pressure on the upper side of the valve being atmospheric the valve will open and the pressure on the upper side will accordingly be reduced. Consequently the difference of pressure on the two sides of the valve will diminish and may not be suflicient to open the reduced by the opening of the valve and the difi'erence in pressure on the two sides of said piston will be sufficient to cause the valve to move to its full open position.

Should the exhausting device fail in its action and the flow of air or gas tend to re.- verse in direction the pressure difference across the valve will diminish still more and the difference in pressure on the two sides of the piston 9 will also be reduced so that the action of the balance weight 4 will be sufficient to close the valve. 3

Various modifications may be made in the construction which is not limited to that shown in the drawing. A spring may be used in place of the balance weight and the upper side of the piston 9 may be exposed to a source of higher pressure than that of the atmosphere, such as for instance that of a supply of steam or water.

I claim as'my invention:

1. In the suction pipe of an air or gas exhausting device, the combination with a non-return valve adapted to be closed by an excess of pressure on the suction or pump side thereof, means adapted to positively close said valve, a cylinder, a piston cooperating therewith, the space in the cylinder on one side of the piston being in communication with the suctionvpipe onthe suction or pump side of the valve, and the space in the cylinder on the other side of said piston being in communication with theatmosphere or a source of pressure above at= mospheric, said piston being so connected with the valve as to assist in the opening thereof when the pressure on. the suction side of said piston is reduced belowth'at on the other side of said piston,

2. In an air or gas-exhausting device, the

combination with a non-return valve adapted to be closed by an excess of pressure on the suction or pump side of the device and having a stem provided with a piston, and means adapted to positively close it, of a cylinder for said piston having a permanently open connection with the suction .pipe on the suction or pump side of the valve. at

least atmospheric'pressureat the other end of the piston.

In an air or gaseexhausting'device, the

combination with'a non-return valve adapt one end ofthepiston and subjected to at subscribed'my name this twenty-second day 7 ofOctober, 1918. V

ARTHUREDWIN LEIGH seams. 

